The Biostatistics Core will (a) develop and maintain the central database of the SPORE and (b) provide biostatistical expertise for all aspects of the SPORE. The central SPORE database will be web based and will house the clinical, tissue and laboratory data of breast cancer patients seen at the Northwestern Memorial Hospital and Evanston Northwestern Healthcare sites. Using current data collection systems as a basis, standardized procedures will be developed for collecting, checking, editing, entering, storing, managing and analyzing the SPORE data. The Biostatistics Core will interact extensively with the Clinical and Tissue Cores for the purposes of developing the database. This core will have expertise in biostatistics, database, technology, systems programming and data entry. This mix of expertise will house all aspects of data management and analysis into this Core, thereby enhancing the efficiency with which SPORE informatics aspects may be viewed and dealt with on a daily basis. In addition to developing and maintaining the database, this core will be responsible for data input, data quality control, statistical analysis and statistical input to research design. This Core will be available at all times to provide input on design or statistical analysis to all SPORE investigators. Scientific input to the SPORE as a whole will be provided as direct input to the Executive Committee regarding the overall research effort of the SPORE. Scientific input by the Biostatistics Core will be provided to individual investigators of interpretation of statistical analyses and writing of manuscripts.